Method for preparing rice



Nov. 20, 1962 YOSHITADA MINAMI 3,065,078

METHOD FOR PREPARING RICE 5 Sheets-Sheet 1 Original Filed May 29, 1957Nov. 20, 1962 YOSI-QHTADA MINAMI 3,065,078

METHOD FOR PREPARING RICE Original Filed May 29, 1957 5 Sheets-Sheet 2Nov. 20, 1962 YOSHITADA MINAMI 3,065,078

METHOD FOR PREPARING RICE Original Filed May 29, 1957 5 Sheets-Sheet 3Nov. 20, 1962 YOSHITADA MINAMI 3,065,078

METHOD FOR PREPARING RICE Original Filed May 29, 1957 Sheets-Sheet 4time in min utes z w F 1 5 20 3o 4o so 6d m 0 0 m m w m a w 4 you @5 .33out pas 0% ox:+d&mau#

3 3: $5. out 8 0 .5 0w: uxs dxol m w time in min utes Nov. 20, 1962YOSHITADA MINAMI 3,065,078

METHOD FOR PREPARING RICE Original Filed May 29, 1957 5 Sheets-$heet 5F5 9 (SA, 158 138 JQZ United States Patent Ofitice spasms l atenteolNov. 2%, 1962 3,065,078 METHGD FER PREPARING REQE Yoshitada Minami,Tokyo-to, Japan, assignor of one-half to Tokyo Shihaura Denisi KabushikiKaisha (known as Tokyo Shibaura Eiectric (3a., Ltd), Kawasaki-sin,.liapan, a corporation of Japan Original application May 29, 1957, Ser.No. 662,436, new Patent No. 2,952,764, dated Sept. 13, 1960. Divided andthis application Apr. 18, 1960, Ser. No. 23,598 3 Claims. (til. 99-30)This invention relates to an improved method for automatically boilingrice, and more particularly relates to a method for automaticallyboiling rice by utilizing electric heat. This application is adivisional application of applicants United States Letters Patent2,952,764, issued September 13, 1960.

The object of boiling rice is to obtain a boiled rice which is easy todigest and is of good taste. Such good rice is obtainable by convertingto a state substantially all starch contained in the rice, and thestarch begins to convert to at state at a temperature of about 60 C. to70 C. or more when the rice is heated in a rice boiler together withsubstantially an equal quantity of water. The time required forconverting to substantially all the starch originally contained in riceto a state or alphonizing it is about from several hours to ten or morehours when heated at 60 C. to 70 C., but this time decreases to abouttwenty to forty minutes when heated at about 100 (3., although exacttime varies to some extent depending upon such factors as the type ofrice, initial temperature of water in the boiler, ambient temperatureand the like.

According to the conventional method for the boiling of rice, arice-boiler containing substantially an equal quantity of rice and Wateris directly heated by town gas flame or by electric heat. By this methodof boiling rice the temperature of the contents of the boiler risesrapidly so that it will reach 100 C. under atmospheric pressure in arelatively short time resulting in a boiling of the water in the boileras well as rapid movement of rice particles which will cause frictionbetween particles of rice. Therefore, the starch on the surfaces of therice particles which has been partially converted to on state will dropofi and will be mixed in water so as to form paste. The formed pastewill result in a boiled rice of bad taste and a portion of the pastewill gush out of the rice boiler and soil the floor or a heatingapparatus supporting the rice boiler. Moreover, by the above-statedconventional method, usual- 1y it is not possible to convert to a: stateall of the starch, because the time of boiling is short. Therefore, itis customary to weaken the heating when boiling or ebullition of waterbegins to prevent severe boiling, thus maintaining the contents of theboiler at the alphanizing temperature or aging temperature over arelatively long period. Such operation not only needs considerableexperience and skill, but also is liable to form burned crust around theinner surface of the boiler because of long heating time involved. ItWill also be clear that such method requires a large quantity of heat.

Accordingly, it is an object of this invention to provide a novel methodof automatically boiling rice by electric heat, which method alwaysyields, without any skill and experience, uniformly alphanized boiledrice of good taste.

Another object of this invention is to provide an improved rice boilingdevice in which the aging period required for alphanizing substantiallyall starch of rice can be set as desired.

Still another object of this invention is to provide an improvedelectric rice boiling device in which the rate of 2 temperature rise atthe initial stage of heating can be moderately alleviated, wherebysevere ebullition and accompanying gush of paste are obviated.

A further object of this invention is to provide an improved electricrice boiling device in which the alphanizing period of rice is dividedinto a predetermined alphanizing period utilizing electric heat and analphanizing period utilizing stored heat, whereby the heat can beeconomicalty utilized.

Briefly stated, according to this invention a rice boiler containingsubstantially an equal quantity of rice and water is disposed within aheating pot in such a manner as to partition a space between the innerwall of said heating pot and the outer wall of said boiler to receive apredetermined quantity of water depending on the quantity of water inthe boiler. As will be more fully explained hereinafter, this water doesan important function in determining the heating and alphanizing period,that is the heating and aging period. There is provided a lid common tosaid rice boiler and heating pot, said heating pot being heated by asuitable electric heating means.

Said heating pot is constructed so as to have a considerably large heatcapacity or a suitable jacket is provided surrounding the whole or aportion of the outer surface of said pot to provide a thermallyinsulated space for heat storage. Thermally associated with said heatingpot there is provided a temperature responsive switching device todeenergize said electric heating means in response to a predeterminedtemperature when the temperature of said pot rises quickly upon thecompletion of evaporation of water contained in the space between therice boiler and the heating pot. In this way the whole period of timerequired for boiling rice is divided into the alphanizing or agingperiod of any desired length by electric heat and the alphanizing oraging period by the heat stored in the rice itself and the variousconstructional parts, making it possible to automatically boil rice in avery successful manner and Without any skill.

For a more complete understandin of this invention reference may be hadto the following detailed explanations in connection with theaccompanying drawings in which:

FIG. 1 shows an elevation, partly in section, paratus embodying thisinvention;

FIG. 2 shows a plan view, partly in section, of the apparatus of FIG. 1with the lid removed;

FIG. 3 is a plan view, as viewed from under of a temperature responsiveswitch mounted on the bottom of a eating pot of HG. 1;

FIG. 4 is a side view of the switch shown in FIG. 3, out along the lineIV-IV and viewed in the direction of arrows;

FIG. 5 is a plan view showing a circular the switch shown in FIGS. 3 and4;

FIGS. 6 and 7 show, respectively, a set of curves of rice boilingcharacteristics obtainable with the apparatus of this invention;

FIG. 8 shows a side view, partly broken away, of another form of thermalswitch which can be used in this invention;

FIG. 9 is a side view, partly broken away, of a switch actuatingmechanism of a combined temperature responsive device and a time delayswitch which can be used in this invention;

FIG. 10 is a connection diagram illustrating still another embodiment ofthis invention provided with means for maintaining the temperature ofthe boiled rice at a predetermined temperature;

of an apspring used in FIG. ll is a view showing vertical section of aportion of another embodiment; and

FIG. 12 is a connection diagram showing a modification of FIG. 10.

Referring now to the accompanying drawings, especially to FIGS. 1 and 2,the automatic rice boiling apparatus embodying this invention isgenerally shown by a numeral it) and comprises a cup-like jacket 11, aheating pot 12 having its edge mounted upon and supported by the upperedge of the jacket and a rice boiler 14 disposed in said heating potwith a space 13 between the side waiis of the pot and boiler. There isalso formed a heat insulating chamber 15 between the jacket it}. and theheating pot 12. At the bottom of the jacket 11 there is provided anopening 17 for adjusting, through this opening, a temperature responsivedevice 31 mounted on the bottom of the heating pot in a manner as willbe hereinafter described.

The opening 17 is closed by means of a bottom plate 18 after theadjustment of the temperature responsive device has been completed, anda plurality of legs 19 made of heat insulating material are attached tosaid bottom plate, as shown in FIG. 1 the bottom of said heating pot ismade thicker than its side wall so as to have an appreciable thermalcapacity.

There is provided a suitable electric heater for heating this bottom. InFIG. 1, this heater is illustrated as a castin sheath wire type electricheater 2% which, as usual, comprises a steel sheath 21, a helicalelectric resistance wire 22 and a heat resistant and electric insulatingmaterial 23 compacted in the sheath. If the sheath 21 is made relativelythick, the heater itself would have a substantial heat capacity. Thesheath wire type heater is shown as the general form of ring shape, butit may be formed in any other suitable shape such, for example, as waveshape and the like, and the heater may also be mounted on the bottom ofthe heating pot by any other suitable means such as Welding.

As shown in FIG. 2, a pair of handles 24- (only one of them being shownin the drawing) made of heat insulating material are attached to theopposite sides of the jacket 11 for convenience of handling. The upperedges of the heating pot 12 and the jacket 11 are fixed together by anysuitable means, for example, by spot welding so as to prevent theheating pot from disengaging from the jacket. At the inner side of theupper edge of the heating pot there is provided a relatively steep slope25 and a relatively gentle slope 26 contiguous to the slope A lid 27whose inner periphery rides on said gentle slope 26 is provided to closeboth upper openings of the inner pct 14 and the heating pot 12. Thus,the tendency of water drops to escape out of the pot is effectivelyprevented by curved path comprised of steep and gentle slopes 2-5 and 26formed at the upper edge of the heating pot. Moreover, by positioningthe upper edge of the rice boiler 14 higher than the abutting linebetween the heating pot 12 and the lid 27, the liquid overflowing theupper edge of the inner pot 14 may be wholly received by the space 13within the outer heating pot 12, so that it is possible to prevent theliquid from running over the upper edge of the heating pot. A pair ofcars 2% is provided at the upper edge of the rice boiler to receive ahook (not shown in the drawing) when it is desired to take out the riceboiler when hot. On the inner wall of the rice boiler there are provideda number of water level indicating lines 29 as is well known in ametering cup.

For effecting manual energization of the electric heater mounted on thebottom of the pot 14 as the beginning of boiling rice and automaticdeenergization thereof upon a predetermined rise of the temperature ofthe heating pot which occurs when the water in the heating pot iscompletely evaporated, in accordance with this invention there isprovided within a heat insulating chamber 15 a temperature responsivedevice such as a thermal switch 31 provided with a manual operatinghandle 34} which exr able contact in a predetermined position.

tends through an opening in the wall of the jacket. This thermal switchmay be disposed, at short distance spaced from the heating pot, in thebottom portion of the heat insulating chamber 15 which surrounds thebottom of the heating pot 12 so that it may be heated by a radiant heatfrom the bottom of the pot to respond to a predetermined temperaturerise in the heating pot, but in such construction the thermal switch hasa tendency not to respond accurately to the predetermined temperaturerise in the heating pot owing to the eifects of ambient temperature.Therefore, in accordance with the most preferred embodiment of thisinvention, the thermal switch 31 is directly mounted on the bottom ofthe heating pot 12 so as to have a heat conductive relation with saidpot.

For facilitating the mounting of thermal switch 31, a heat conductingstud 32 is provided on the bottom of the heating pot 12 integraltherewith and the thermal switch 31 is mounted on said stud directly andin heat conductive relation.

A preferred form of the thermal switch 31 suitable for use in thisembodiment is shown in FIGS. 3 and 4. A base plate 33 on which aremounted various portions of the switch as hereinafter described is fixedto said heat conducting stud 32 by means of screws 50 and 68 and thelike. One end of a bi-rnetallic element 34 is disposed on a block 35. Asecond block 36, a leaf spring 37 and a third block 70 are superposedeach other on that end of the bi-metallic element and these elements areclamped to said base plate by a screw 38, said blocks 35, 36 and 70being preferably made of metal. A spring plate 39 which hasconfiguration of figure 8 as shown in FIG. 5 is mounted through itstongue 4t) to the free end of said bi-metallic element, and one end ofthe switch operating handle 30 is attached to another tongue 41 providedat the central portion of said figure 8 shaped spring plate 39 at theside opposite to said tongue 40. A pair of cars 42 are formed bypunching out one end of the tongue 41 to form a recess 43 between saidears. One leg of a generally V-shaped plate 45 made of resilientmaterial is mounted on a pedestal 44 formed at the left hand end of thebase plate 33 by means of a screw 46. As shown in FIG. 4, the curved endof the other leg of the spring plate 45 engages with said recess 43formed between the ears 42 of a pair. Thus said plate 435 acts as afulcrum for the tilting motion of the operating handle 30. In order toenable a slight adjustment of the height of the fulcrum, one leg of theplate 45 is curved slightly and the extent of this curve is madeadjustable by an adjusting screw 47 which passes through the plate andis screwed in the pedestal 44.

Thus by tightening the screw 4'7, the fulcrum of the operating handlewill be lowered and vice versa.

A pair of contacts 48 and 49 are provided as shown in FIGS. 3 and 4 forcontrolling the energizing circuit of said sheath wire type heater. Aswill be clear from FIG. 3 the stationary contact is supported through asuitable insulation on a bracket 51 which is integral with the baseplate 33 and is connected with one terminal of said sheath wire typeheater by way of a conductor 69. As shown in the drawing, the movablecontact 49 is supported on one end of a conductive strip 52 made ofresilient material, the other end of said strip being supported by anarm 53 which in turn is insulatedly supported by another bracket 54,thus maintaining the mov- This movable contact is connected to one poleof a plug switch 56 shown in FIG. 1, while the other end of the sheathwire heater is connected to the other pole of said switch, thusconnecting said pair of contacts to a source of electric supply inseries with the heater. As shown in PEG. 4, the arm 5?. supporting themovable contact 49 is slightly curved upwardly so that the movablecontact may engage with the stationary contact to make an electriccircuit even when no external force is exerted on the arm 52.

spasms FIG. 4 shows an operated position in which the contacts areclosed.

For moving the arm 52 in a direction to open the contacts, a cylindricalpiece 56 made or" electric insulating material is attached to theunderside of the arm 52 in such a manner that its lower end lies over anoperating member 57 provided on the right hand end of the handle 3%.Counter clockwise movement of the handle around the pivot formed bycurved end of said V-shaped plate 45 bring the operating member 5; toengage with the cylindrical piece 56, thus moving it upwardly. Thus thearm 52 is also pushed upwardly to separtte the movable contact 49 fromthe stationary contact $8. The figure S shaped spring plate 39 not onlyacts as a spring for effecting snap action, but also acts as a biassingspring for locking the movable contact in the open and closed positions.For assuring the latter action, the figure 8 shaped spring plate isnormally held in a slightly flexed state by some pressure imposed uponthe central portion thereof from both sides. By this arrangement, it ispos sible t look the handle 30 in the open position shown by full linesand in the closed position shown by dotted lines in FIG. 4.

The automatic operation of the switch from the closed position shown inFIG. 4 to the open position is as follows:

When the bi-metallic element 34 is subjected to a heating actionexceeding a predetermined value, it flexes in a clockwise directionaround its right hand fixed end. Due to this fiexure, the free end ofthe element causes one end of the figure 8 shaped spring plate 39 tomove upwardly and when this flexurc exceeds a predetermined value thefigure 8 shaped spring plate moves with snap action from the positionshown in FIG. 4 to upwardly curved position for moving the handle 3i tothe position shown by dotted lines to separate the contacts. Foradjusting the temperature at which the contacts separate to apredetermined temperature, an adjusting screw 53 is provided, said screw58 cooperating with the spring 37 for imparting an adjustable opposingforce to the free end of the bi-metallic element. For this purpose aprojection or a button 59 is provided at the free end of thebi-rnetallic element opposite to the free end of the spring plate 37. Acoil spring so is wound around the adjusting screw 58 and the both endsof said spring are locked t the block 70 so as to prevent accidentalmovement of the screw after it has been set.

The upward and downward movements of the fulcrum formed by said t-shaped plate :25 also serve to the adjustment of said predeterminedtemperature at which the separation of the contacts occurs. Thuselevating of the fulcrum delays the occurrence of the snap action, thuscausing the contacts to separate at a relatively higher predeterminedtemperature, while lowering of the fulcrum fastens the instant at whichthe snap action occurs, thus causing the contacts to separate at arelatively lower predetermined temperature. Further the adjustment ofcontact separation can also be effected by an adjusting screw 62 screwedin a projection 61 attached to the base plate 33, and connected to thebi-nietaliic element. By adjusting this screw, the lei-metallic elementis adjusted in the longitudinal direction for increasin or decreasingthe bending force impressed upon the figure 8 shaped spring plate 39.For enabling this adjustment, a suitable oblong slot (not shown) isprovided at the fixed end of the bi-metallic element.

If the bi-metallic element is pushed to the left to increase bendingforce acting upon the figure 8 shaped spring plate 39, the temperatureat which the separation of the contact occurs will be increased, whileon the contrary, if the bi-metallic element is drawn to the right todecrease the bending force acting upon the bi-metallic element, theseparation of the contacts would occur at a relatively low predeterminedtemperature.

Having completed the explanation relating to constructions and functionsof various parts of the apparatus of this invention, the method ofboiling rice of this invention will now be described.

Referring again to FIG. 1, the rice boiler 14- is first taken out and aquantity of suitably washed rice 63 and water 64 of substantially thesame quantity as the rice are placed in it. Generally, the waterquantity is dependent upon the quantity of rice, but it is most convenicut to use the water level lines 29 which are calibrated by the quantityof rice to be charged in the boiler. Next a suitable quantity of water65 is poured into the heating pot.

The quantity of this water varies in accordance with such factors as thequantity of water in the rice boiler, type of starch of rice and thelike, but it is preferable to use this water in a quantity amounting tosubstantially 4 to 50% of the water quantity in the rice boiler. Thiswater in the heating pot serves as an indirect heating medium for thecontents in the rice boiler and also functions to establish apredetermined heating and aging period set in accordance with thisinvention. After inserting the rice boiler 14 containing rice and waterinto the heating pot 12, lid 27 is placed over the boiler and heatingpot as shown in FIG. 1, and the operating handle is moved to the contactclosing position shown in FIG. 4.

Then the sheath wire type heater '20 is energized from a suitable sourceof electricity and begins to heat the heating pot. Initially the water65 in the heating pot 12 is heated, which in turn heats up the contentsin the rice boiler. Steam generated in the heating pot rises along theside wall of the rice boiler while heating it and then enters into theupper inside portion of the boiler around the upper edge thereof andheats the contents. As a result, the contents in the rice boiler areheated from all directions, resulting in a uniform heating. it should beemphasized that owing to the presence of water 65 in tr e heating pot,the rate of temperature rise of water in the rice boiler is naturallyalleviated so that ebullition never occurs. Thus the rice particles inthe boiler do not move violently as in the case of the conventionalmethod of boiling rice, but stand still, so that there is no frictionbetween the particles and the tendency of removal of surface starch toform paste is effectively precluded. This mode of heating is continueduntil the water 65 in the heating pot is completely evaporated.

Generally it takes about 20 to minutes to complete the evaporation ofwater in the heating pot, this time of course depending upon thequantity of water 65. While this water is evaporating and decreasing inquantity, the rate of temperature rise in the rice boiler will graduallyincrease. But, during this relatively long period of time the rice inthe boiler is adequately heated and aged to alphanize a substantialquantity of starch contained in the rice.

Upon completion of evaporation of water in the heating pot 12, thefactor that prevents the temperature rise beyond C. in the pot isdiminished resulting in a rapid temperature rise of said pot. Responsiveto this rapid rise in temperature the thermal switch 31 associated withthe heating pot operates at a predetermined temperature to separate thepair of contacts 48 and 49 to demergize the heater circuit, as has beenpointed out hereinbefore. Since the heating pot is constructed so as tohave a relatively large heat capacity, it will absorb and store asubstantial quantity of heat during rice boiling. If desired, arelatively massive steel plate or the like heat storage body not shownin the drawing may be attached to the bottom of the heating pot forincreasing the heat storage capacity as will be more fully explainedlater. This is particularly desirable when the heating pot is made ofaluminum or the like having relatively low specific heat. Furthermore,since there is provided a heat insulating space 15 between the heatingpot and the outer jacket 11, heat loss from the heating pot is small.Thus the temperature of the boiled rice is maintained by the heataoeaova stored in the heating pot and the rice itself substantially atthe temperature of the moment when the switch is opened, over arelatively long period of time after the thermal switch is operated.Accordingly, the contents in the rice boiler is maintained at thetemperature necessary for alphanization over a suitable period of timeafter the deenergization of the heater, resulting in a completealphanization of the rice. In the above, the initial half period ofheating and alphanization can be controlled by the quantity of water 65in the heating pot. That is, the more water 65 there is, the longer thetime to open the thermal switch 31, and vice versa. It is to beunderstood that the quantity of water 65 to be poured into the heatingpot is to be selected to the minimum quantity necessary to effect thedesired alphanization of rice. This is necessary to minimize theelectric power required for heating, thus providing most economic riceboiling. For example, for the ordinary non-glutinous rice it issuflicient to select the quantity of water 65 to an amount ranging from4- to 50 percent based on the amount of water in the rice boiler, whilefor glutinous rice to about 30 to 50% of the quantity of water in therice boiler.

FIGS. 6 and 7 show curves obtained by two different types of test ofboiling rice utilizing the automatic rice boiling device of thisinvention. FIG. 6 shows two curves 66 and 67 showing the relationbetween the temperature rise in degrees centigrade of rice and heatingpot and the time in minutes when 1 litre of water and 1 litre of rice ischarged in the rice boiler and 0.1 litre of water is charged in theheating pot which corresponds to 10% of the water in the rice boiler andan electric heater of the rated capacity of 100 v., 620 w. is used. Thecurve 66 shows how the temperature of heating pot changes with'timewhile the curve 67 shows the temperature change of rice with respect totime. This test was carried out under an ambient temperature of 11 C. Aswill be noted from these curves, the temperature of both the heating potand rice rose relatively gradually over the initial period of 30minutes. More particularly, during this period of 30 minutes thetemperature of the heating pot had reached to 120 C. and that of therice to about 84 C. from the initial temperature of 11 C. During thiscourse of heating, rice particles in the boiler did not move or joggleat all and were uniformly heated.

Alphanization of rice began at about 60 C. upon elapse of about minutesafter initiation of heating and the rate of alphanization was increasedwith the rise of temperature. At about 30 minutes after the initiationof heating, evaporation of water in the heating pot was completed andthereafter the temperature of the pot has risen quickly to about 200 C.within relatively short time, at this point the thermal switch 31 wasoperated to open the pair of contacts 48 and 49. The temperature of ricewas made to rise to 100 C. with the temperature rise of the heating pot.After the switch had opened the temperature of the rice was maintainedat a substantially constant value of 100 C. for the interval of 17minutes from 38 minutes to 55 minutes by the heat stored in the heatingpot and the rice itself. As is clear from the curves, the rice washeated and aged by the electric heat and the stored heat over a periodof 35 minutes and essentially the Whole of the rice was converted toalpha state. It took about one hour to complete the whole rice boilingcycle during which the electric heater was energized for only 38minutes.

FIG. 7 shows a test result of this invention using different type ofautomatic rice boiling apparatus according to this invention with about1.8 litres of rice and same quantity of water charged in the rice boilerand 0.14 litre of water in the heating pot and using an electric heaterof the rated capacity of 100 v., 840 w. This test was carried out underthe ambient temperature of 16 C. Curves 66' and 67' show, respectively,the temperature of the heating pot and the temperature of the rice. Inthis case too, alphanizing eriod of 35 minutes by electrio heat andstored heat was obtained during the whole rice boiling cycle of aboutone hour, and the energizetion time of the heater was nearly 40 minutes.

As will be clear from the above explanation, according to thisinvention, by selecting the quantity of water in the heating pot to adesired value, it is possible to control the periods of time requiredfor heating and aging, that is the alphanizing period, to anypredetermined value, in other words, it is possible to adjust the wholealphanizing period, thereby to alphanize sub stantially the whole of therice, thus enabling to obtain the boiled rice of good taste anddigestion. Furthermore, it is always possible to obtain excellent boiledrice without any skill, because the time interval required for thepredetermined degree of alphanization can be auto matically set by waterquantity in the heating pot and the temperature switch responsive to thetemperature of heating pot. Moreover, according to this invention, therice in the rice boiler is indirectly heated by means of water containedin the heating pot, so that quick temperature rise of rice can beprevented and the rice particles do not joggle, thus paste like water isnot formed in the rice boiler. Moreover, according to this invention,since any electric heat is not applied during the whole period necessaryfor alphanization of rice, any burned crust is not formed and mosteconomical utilization of electricity can be realized.

In the above example, thermal switch of the type that can not beexternally adjusted was used. But, some people like relatively hard ordry boiled rice while others like relatively soft or wet one. Thewetness of a boiled rice can be adjusted to some extent by adjusting thequantity of water in the heating pot.

More particularly, by increasing the quantity of water in the heatingpot, the time required for the complete evaporation thereof islengthened so that various parts of the apparatus may be heated forlonger period of time to store more heat. This stored heat is thereaftergiven .to the boiled rice and serves to dry it. On the contrary, ifwater quantity in the heating pot is decreased, the thermal switch wouldoperate at a more earlier time so that less heat may be stored in theapparatus, resulting in a less dried or wet boiled rice. However, it isnot desirable to change to a large extent the quantity of water in theheating pot, because this quantity is an important factor for attainingthe desired heating and alphanizing period. By the reason above stated,it is advantageous to construct the apparatus such that the above objectmay be obtainable, without changing water quantity in the heating pot,by adjusting the time interval between completion of evaporation of theWater contained in the heating pot and cut ofi of the electric heater.

FIG. 8 shows a modification of this type constructed in accordance withthis invention. In the drawing, numeral 134- indicates a temperatureresponsive bimetallic element of the same general character as abovedescribed, the right end thereof being fixed on a block 135 mounted on abase plate 133. The left end of the bi-metallic element is connected tothe switch mechanism through a figure 8 shaped spring plate 139, thedetail of the switch mechanism being not shown in the drawing since itmay be the same construction as above explained.

Blocks 135, 136 and 170, bi-metallic element 134 and a spring plate 137superposed one another as shown in the drawing are clamped to the baseplate 133 by means of a screw 138. In the thread of the projection ofthe block 170 is screwed a screw 158 which adjusts the biasing force ofthe spring plate 137 upon the bimetallic element. One end of anadjusting lever 159 is attached to the head of the screw 158 and theother end extends through a hole 161 in a scale board 160 which ismounted on a jacket not shown. When the adjusting lever 159 is moved ina forward direction, that is away from the paper as viewed in FIG. 3,the biasing force applied upon the bi-metallic elemett 134 by the springplate 137 will be increased and the bi-metallic element will break thecontacts at a more higher temperature of the heating pot, thus more dryboiled rice will be obtained. Conversely, when the adjusting lever 159is moved in the opposite direction, biasing force of the spring platewill be decreased and the bi-metallic element will cause the contacts toseparate at a more lower temperature of the heating pot, thus moderatelywet boiled rice can be obtained.

FIG. 9 shows another modification of this invention in which a timeswitch 162 is combined with the bimetallic element 134 of the samegeneral construction as explained in FIG. 8 for adjusting the timeinterval between the completion of evaporation of water in the heatingpot and deenergization of electric heater.

In this embodiment, the bi-metallic element 134 is so related to thetimer 162 suitably mounted on the jacket, not shown, that it will pushan actuating rod 163 of the timer when deflected upwardly. Although thedetails of construction of the timer have been omitted from the drawing,it is to be understood that the timer has a pair of contacts which areclosed when a handle 164 is turned from a position marked P which meansfast to a position marked S which means slow and are arranged to beopened after a predetermined time inter val determined by the handle 164and the scale 165 when the bi-metallic element pushes the actuating rod163. Thus it is able to provide boiled rice of any desired degree ofdryness.

FIG. 10 shows a still further modification of this invention which canmaintain the boiled rice in warm state over a long period of time. Asshown in FIG. 10 the electric heater 120 is connected across theterminals 17% and 171 through a pair of parallel connected thermalswitches 131 and 131'. The thermal switch 131 is of generally the sametype as the thermal switch 31 hereinbefore explained in connection withFIGS. 3 and 4 and opens its contacts in response to a predeterminedtemperature rise of the heating pot. The thermal switch 131', however,is set to maintain a constant temperature, say about 70 C. necessary tomaintain the boiled rice in warm state.

The operation of this embodiment is as follows:

A pair of terminals 170 and 171 are connected to a suitable source ofelectric supply, and the thermal switch 131 is closed. Since at thistime the temperature of the rice boiling apparatus is still low, thecontacts of the switch 131' are also closed and the electric heater 12%is energized through the contacts of both switches 131T and 131. Whenthe temperature of the heating pot exceeds 70 C., the thermal switch 131will open its con tacts. With the advance of the rice boiling cycle, thethermal switch 131 will open its contacts in response to a predeterminedtemperature rise of the heating pot which occurs after the water thereinis completely evaporated.

It is to be remembered that the switch 131 is of the type that it can bereclosed only by manual operation. After the predetermined wholealphanization period by heat is completed, the temperature of theheating pot begins to decrease below 166 C. until finally the thermalswitch 131' closes its contacts to reenergize the electric heater 120.

Thereafter the temperature of the boil-ed rice is maintained at about 70C. by the well known intermittent action of the thermal switch 131.

in a modification shown in FIG. 11 which shows a vertical section of hebottom portion of the rice boiling apparatus with the outer jacketremoved, the bottom hit of the heating pot 12 containing the rice boiler14 is provided with a unitary projection =31. This projection not onlyserves as a post for mounting a thermal switch 31, but also as a heatconducting member to conduct heat from said bottom to the thermal switch31.

On the outer surface of said bottom there is also provided an annulargroove 82 in which is disposed an annular fiat electric heater 83comprising an annular insulating plate 84 such as mica, a resistancewire 85 helically wound on said insulating plate and an insulating cover36 enclosing the resistance wire. A heat storing plate 1%? having aconjugate annular groove 88 to receive the electric heater S3 is placedover the heater and fixed to the bottom 81) by means of screws 89.

The heat storing plate 87 is provided with an opening 9%? through whichthe projection 31 extends downward. The heat storing plate is made ofsuch a material having larger specific heat, that is larger heat storingability than aluminum and the like from which the heating pot is usuallymade of, for example, as iron, steel, copper, lead ail-o3 a ceramic andthe like, so as to store substantial amount of heat during the course ofheating by electricity and maintain the temperature of the heating potas well as the rice boiler at about 106 C. by the stored heat for asuitable period of time necessary to complete alphanization of riceafter the electric heater has been deenergized. This plate is preferablymade of iron, because it is most cheap.

instead of providing two thermal switches 130 and 131 as shown in FIG.16, a normal electric heater and an auxiliary electri heater 96 whichare selectively energized by a double throwtype oi-metal 97 may beemployed as shown in FIG. 12. During heating and boiling rice thebimetal is in the position shown in FIG. 12 with its contact engagedwith a stationary contact to energize the normal electric heater 95, butafter a predetermined temperature rise has been attained it deflects inthe downward direction to engage with the other contact 99 to energizethe auxiliary heater )6 for maintaining the temperature of the boiledrice at a temperature, say at about 70 to 80 C., suitable to eat.

Although not shown in the drawings a suitable device may be provided forthe bi-metal for locking it in the position engaging with lower contact.Also a suitable pilot lamp or lamps may be provided to indicate theenergization or deenergization of electric heater. Furthermore, in theembodiment shown in FIGS. 1 and 2 the outer jacket 11 is shown tocompletely enclose side and bottom walls of the heating pot with a heatinsulating space or chamber 12 therebetween, but this is not alwaysnecessary and in some case the jacket may be provided for enclosing onlya portion of the heating pot, i.e. the bottom portion thereof which hasthe desired heat storage functioo.

While this invention has been shown and described in connection withsome preferred embodiments thereof, this invention is not limitedthereto and includes any modifications and alterations as fall withinthe true spirit and scope of this invention.

What 1 claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. The method of preparing rice by converting the natural rice starchwith a minimum of heat and loss of the natural starch comprising thesteps of (a) adding a substantially equal volume of rice and water to acooking zone; (b) adding a quantity of control water to heating zone tocontrol the consistency of the prepared rice after the natural ricestarch has been converted, the amount of said control water rangingapproximately 450% the amount of water in said cooking zone; (0) saidcooking and heating zones being in communication and substantiallyenclosed from the atmosphere; (d) applying heat to said heating andcooking zones and converting all of the control water to steam andeffecting partial conversion of the rice starch; (e) terminating theapplication of heat in relation to the amount of control water used andwhen the temperature in said cooking zone is below that to affordcomplete conversion of the rice starch; and (f) permitting completion ofthe conversion of the rice starch by virtue of the heat stored in theheating and cooking zones in the absence of the application of externalheat while the zones References flied in the file of this patent remainenclosed from the atmosphere.

2. The method of claim 1 wherein the heating of the UNITED STATESPATENTS cooking and heating zones is controlled so that the cookchandlerP 16) 1957- ing zone always remains at a substantially lower tempera- 5tnre than the heating zone.

3. The method of claim 1 wherein the application of heat isautomatically controlled an heat is maintained from approximately 20 to40 minutes.

OTHER REFERENCES Everybodys Cook Book, 1924, by Lord, Herny, Holt andC0. (New York), pages 198l99.

1.THE METHOD OF PREPARING RICE BY CONVERTING THE NATURAL RICE STARCHWITH A MINIMUM OF HEAT AND LOSS OF THE NATURAL STARCH COMPRISING THESTEPS OF (A) ADDING A SUBSTANTIALLY EQUAL VOLUME OF RICE AND WATER TO ACOOKING ZONE; (B) ADDING A QUANTITY IF CONTROL WATER TO HEATING ZONE TOCONTROL THE CONSISTENCY OF THE PREPARED RICE AFTER THE NATURAL RICESTARCH HAS BEEN CONVERTED, THE AMOUNT OF SAID CONTROL WATER RANGINGAPPROXIMATELY 4-50% THE AMOUNT OF WATER IN SAID COOKING ZONE; (C) SAIDCOOKING AND HEATING ZONES BEING IN COMMUNICATION AND SUBSTANTIALLYENCLOSED FROM THE ATMOSPHERE; (D) APPLYING HEAT TO SAID HEATING ANDCOOKING ZONES AND CONVERTING ALL OF THE CONTROL WATER TO STEAM ANDEFFECTING PARTIAL CONVERSION OF THE RICE STARCH; (E) TERMINATING THEAPPLICATION OF HEAT IN RELATION TO THE AMOUNT OF CONTROL WATER USED ANDWHEN THE TEMPERATURE IN SAID COOKING ZONE IS BELOW THAT TO AFFORDCOMPLETE CONVERSION OF THE RICE STARCH; AND (F) PERMITTING COMPLETION OFTHE CONVERSION OF THE RICE STARCH BY VIRTUE OF THE HEAT STORED IN THEHEATING AND COOKING ZONES IN THE ABSENCE OF THE APPLICATION OF EXTERNALHEAT WHILE THE ZONES REMAIN ENCLOSED FROM THE ATMOSPHERE.